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318 camshaft

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318 camshaft

tannerlowe tannerlowe
New User | Posts: 30 | Joined: 01/09
Posted: 04/12/10
01:54 PM

i have a 72 duster with a 78 dodge diplomat 318 four barrel i want to change the cam but will i have to change rocker arm or valve springs  

drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 04/12/10
03:31 PM

You will not have to change rocker arms unless you change from a hydraulic lifter cam to a solid.
You will have to change valve springs. A good cam for this engine is the Comp. Cams CL20-221-3 hydraulic. This is a split pattern cam and will give great performance from 1000-5200rpm. It is 256/268 duration @ .050 with 447/454 lift. This is a very good street performance cam.
Good Luck.  

tannerlowe tannerlowe
New User | Posts: 30 | Joined: 01/09
Posted: 04/12/10
05:23 PM

will this cam alter how my car will idle and will the power boost be very noticable  

.71RedneckStroker_ .71RedneckStroker_
Guru | Posts: 848 | Joined: 11/09
Posted: 04/12/10
06:19 PM

Here's a dang good un.   http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=693&sb=2  

I can put a square peg in a round hole. Gimmie that hammer.

drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 04/12/10
08:23 PM

The exciting thing about this cam is it performs right off idle with a stock converter and gear. Will it make a difference and sound better, YES! A stock 318 cam has specs around 370" lift intake, and 400 lift exhaust. So you can see this cam will build some solid power and be totally streetable. However it is a hydraulic cam, this means you will have to run a quality motor oil with a sm/sl rating. 15w/50 mobil one synthetic meets this requirment. You can also run reg. oil and put some zinc additive in it. Either way expect to spend more money for your oil changes.  
Doc Cool  

badsport badsport
Enthusiast | Posts: 385 | Joined: 01/10
Posted: 04/13/10
05:03 AM

Here is a thread for you to check out.


Move Over People Are Racing

drmopar drmopar
Guru | Posts: 1445 | Joined: 02/08
Posted: 04/13/10
11:27 PM

Problem is the thread has some miss information. When I plug in the cam quest 6 program the .454 lift cam makes 340 HP with some simple mods and 390 ft. lbs of torque. What magic was involved in getting a 318 to produce such numbers with such a mild cam. Simple, RpM dual plane intake, 600 cfm carb, 9-1 compression, 1.88/1.60 valves. Pocket porting, open headers. In a 3000 lb car these are stout numbers and will dip into the very low 14's with nothing more than a set of 3.55 gears. Not bad for a daily driver. With a little tuning and a stiff tail wind a 13.99 is probably in the package.
Good Luck  

MeLuVzMaCuDa MeLuVzMaCuDa
New User | Posts: 1 | Joined: 10/12
Posted: 10/25/12
09:33 AM

hi there i have a 1999 dodge durango with a 318 will this cam work in it? im looking at a mopar cam thats almost exact same specs but would i like to get that muscle car sound as most of us would


451Mopar 451Mopar
User | Posts: 220 | Joined: 07/10
Posted: 10/25/12
11:34 PM

drmopar, that cam looks nice. You have a typo, the advertised duration @ 0.006" is 256/268.  The duration @ 0.050" is 212/218.
I plugged the data into the Dynomation 5 software using wave-action modeling, I got 271 HP @ 4,400 RPM and a nice, near flat, torque curve with a peak if 363 ft/lbs @ 2,600 RPM.
Here is the basic info I input for the sim:
318 engine, 9:1 compression, 360 #915 heads 1.88"/1.60" valves unported, Flow 196/129 @ 0.500", Dual plane hi-flow intake and 600 cfm 4-bbl.  I just guessed the runner length of about 7", plenum of 2.5sqin, min port are a 1.5sqin, cam lobe profile loaded in for the comp 20-221-3 cam file, 1.5:1 rocker arms, small tube 1.5" headers, 28" primary, 9" collector.  Numbers were the same when modeled with or without mufflers.
The Dynomation 5 sim allows inputs of actual head flow numbers, the cam quest program probably overestimates the head flow.  The 2-valve head, low performance, stock ports selection may be closer?

Just changing the head flow numbers to a ported head with 2.02" intake valve and flowing 220/148 cfm @ 0.500" jumped power to 317 @ 4,800 RPM, and 374 ft/lbs torque @ 3,800 RPM.  

pepsi1 pepsi1
User | Posts: 150 | Joined: 10/11
Posted: 10/27/12
12:13 AM

Don't go crazy on the duration. Usually anything more then .230/.230 and .450/.450 at .050 lift, is the limitation before the idle goes crazy. Keep things in order of .222* to .224* duration@ .050. Then your idle will not go crazy when you put the trans in gear.

You want to wake your car find out what rear gear ratio you have. A 3:50 to 3:70 rear gear is a nice accelerating gear. You'll see the difference.

wyrmrider wyrmrider
New User | Posts: 5 | Joined: 01/13
Posted: 01/11/13
04:12 PM

I do not think Drmopar meant 256@.050  most likely at .006
256@006 a good grind designed for the Mopar lifter should have about 204@.050 and over .300 at the cam lobe lift at least .450 with 1.5 rockers

something is wrong
a Chrysler hyd cam cannot have 212@.050 with 256@.006

most chevy cams with 212 (the popular 212-224) are only going to have 420-430 but are 270 cams on the seat